"Your department lost track of a kid," said Rep. David Linsky, chair of the House Committee on Post Audit and Oversight. "That’s absolutely inexcusable."

Roche repeatedly blamed three DCF workers who have been fired for what she called a gross disregard of duty.

Roche said Gov. Deval Patrick's proposed $9.2 million investment in the department will help prevent such cases in the future.

"It will allow us to increase the number of staff we have in the screening unit, increase the number of staff in the investigation unit and allow us also to put more social workers in the regional offices," said Roche.

Roche acknowledged only a third of case workers are licensed social workers and said she is working with the union to make that a condition of employment.

Roche told lawmakers she is confident the 36,000 children in the DCF system are safe.

"Can you give me that assurance that there are no other Jeremiah Olivers out there?" asked Linsky.

"Yes," replied Roche.

The Office of the Child Advocate released a report which found the caseloads in the Leominster office, one of the busiest in the state, compounded the failures but do not explain or excuse them.

Child Advocate Gail Garinger said Thursday that the heavy workload "provides a context" but does "not explain or excuse the failures in basic protective service casework and supervision that occurred" with the family of Jeremiah Oliver. Garinger says regular visits are the "most basic obligation of front-line social workers."